Ceboruco volcano in the western Trans-Mexican Volcanic Belt is one of the eleven most active stratovolcanoes in Mexico. Due to its recent eruptive history including a large Plinian eruption ~ 1000 years ago, the AD 1870 eruption, and recurrent recent seismic activity, it seemed highly appropriate to construct a hazard map in order to be prepared for future eruptions and their associated hazards. Ceboruco volcano eruptions are predominantly effusive; however, it also has been characterized by a great variability of eruptive styles throughout its record of activity. In fact, some eruptions comprise a significant diversity of volcanic processes, including lava flows, tephra fallout, ballistic emission, pyroclastic flows and surges, and lahars. In this work, we present (1) an integrated and simplified hazard map and (2) more detailed scenario-based hazard maps showing the areas affected by the different expected volcanic phenomena attempting to account for this great diversity of eruptive processes. The maps represent the basis to identify the main hazard zones during a future eruption and the related impacts on population and infrastructure within the area of influence of Ceboruco (~ 700 km 2 ), as well as for undertaking subsequent vulnerability and risk analyses. The maps provide a tool to develop measures of prevention and mitigation of volcanic hazards (preparedness of the population, establishment of evacuation routes and refuges, etc.), as well as for decision-making by authorities during territorial planning (urban expansion for example). The integrated simplified hazard map can also be a tool for dissemination purposes, in order to create awareness of associated hazards derived from a possible future activity of the volcano among the public in general. This is important because in the western sector of the Trans-Mexican Volcanic Belt (and specifically in the State of Nayarit) most volcanic edifices (with the exception of Colima volcano) are closedvent volcanoes (sealed volcanic vent vs. open-vent systems) with long repose periods (up to ~ 16,000 years for example in the case of San Juan volcano 60 km to the W), a situation that consequently and unfortunately has led to a practically nonexistent volcanic risk perception.

Of the 48 volcanoes in Mexico listed as potentially active by the National Center for Disaster Prevention (CENAPRED), Ceboruco, located in the western Trans-Mexican Volcanic Belt, is considered among the 5 most hazardous. Its recent eruptive history includes a large magnitude Plinian (VEI 6) eruption~1000 years ago and the historical 1870-1875 vulcanian (VEI 3) eruption, as well as recent fumarolic and seismic activity. Ceboruco is a relatively young (< 400,000 years) stratovolcano characterized by abrupt changes in eruptive behavior. Individual eruptive episodes have great variations in style (effusive andesitic to highly-explosive rhyodacitic) and duration. These factors complicate hazard assessment. Three main eruptive scenarios of different magnitudes (large, intermediate, small) and eruption characteristics (likelihood of occurrence: high, medium, small) have been identified and will be presented as a background to build the volcanic hazard map for Ceboruco volcano (presented in part II of this work). Here, we report on the detailed eruptive history, with emphasis on the volcanic products of each of the eruptions, in order to identify those deposits that can serve as a reference for calibrating the modeling software (Tephra2 and Hazmap for ash fallout, Eject! code for ballistics, Etna Lava Flow Model for lava flows, Titan2D for pyroclastic density currents, and Flo-2D and LaharZ for lahars) that will be used in further steps to simulate different volcanic phenomena and lead to the construction of the hazard map.

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